1. Field of the Invention
The present invention relates to a power supply, more particularly, to a power supply with mixed mode batteries, which includes different types of battery modules operating together to supply power to a load.
2. Description of Related Art
The use of electrical energy has made the life of human beings much easier. Various electrical apparatuses have become so useful in everyday life that they are considered necessities. Therefore, the assurance of a continuous supply of power has also become very important. Accordingly, the UPS (Uninterrupted Power Supply), which is a battery based source of power to a load when the utility power is abnormally low or unavailable entirely, or a typical portable electrical appliance/machine that is designed to be used with or without the utility electricity is provided. FIG. 7 shows a block diagram of a conventional UPS, including a battery module (71), an AC to DC converter (72), a charger (73), a sensor unit (74) and a DC to AC converter (75). When utility power is available, it is converted by the AC to DC converter (72) to constantly charge the battery module (71) via the charger (73). Once the sensor unit (74) detects that the utility power is below a preset normal threshold including being completely unavailable, the battery module (71) supplies power, which is optionally converted by the DC to AC converter (75), to a load. The duration that a UPS can supply power varies from a few minutes to hours, depending on the performance of the battery module. Obviously, it is desired to have a battery module that can supply power as long as possible. In addition, the battery module of the UPS should be able to endure sudden surges in demand for electrical energy. However, no single existing battery technologies can satisfy all the requirements of an ideal UPS. Some of the batteries can last for a long time but cannot accommodate the sudden surges in demand for electrical energy, while others that can meet the sudden surges in demand for electrical energy can only last for a short period of time. Therefore, there is a need to improve the power supplying capability of battery module.